You still wouldn't be about to distinguish the output from noise unless you know the key or you've broken the cryptography, even if you know every bit of the message. Isn't it neat?

And yes, as the other comment points out it's only one source among multiple.

If your attack vector is breaking and entering, that's a pretty effective cybersecurity mechanism.

But even if it happened, this is one of many additive entropy mechanism, removing or controlling only one source would not be sufficient for any attack.